A couple of things can stop/crash pihole-FTL:
-
On Raspberry Pi's, under-voltage can ocure:
503 Service Not Available - #26 by deHakkelaar -
Running out of memory.
Maybe bc dbase grows too large bc of DNS loop or other excessive querying:
DNS not running, FTL down - #24 by deHakkelaar -
Filesystem errors:
Pihole intermittently stops resolving until hardware reboot - #14 by deHakkelaar
Or maybe a power saver if connected via WiFi:
And I'm probably missing a few others